Growth variation, settlement, and spawning of gray snapper across a latitudinal gradient

Newly recruited juvenile gray snapper Lutjanus griseus were collected each fall for two consecutive years (2000 and 2001) from sites in Florida and North Carolina. Spawning, settlement, and growth patterns were compared across sites based on otolith microstructure. Larval otolith growth trajectories were generally similar for larvae from different sites and years; however, the mean pelagic larval duration (PLD) was 1 d longer for fish from North Carolina than for fish from the more southern sites. As a result, fish were larger at settlement to North Carolina. Estimated juvenile growth rates ranged between 0.62 and 0.88 mm/d and differed across sites and years, growth being generally faster at the southern sites. Water temperature accounts for some of this variability; however, site-specific differences in other factors probably contributed to some of the observed differences in growth. Back-calculated spawning patterns showed a lunar association with the new and first-quarter moons at all sites except for North Carolina. Settlement patterns were lunar cyclic as well: settlement pulsed during the third-quarter and new moons at all sites, and in North Carolina an additional pulse associated with the full moon was present. Patterns of larval and juvenile growth coupled with recruitment dynamics across the latitudinal gradient are consistent with northward Gulf Stream transport of larvae from southern spawning sites.